1. Field of the Invention
The invention relates to an atomizer particularly for use in devices for inhalation therapy.
2. Related Art
Inhalation therapy is not only used for treating respiratory tract diseases but also, to an increasing extent, for administering other medicinal active substances. In this kind of therapy, the substance is offered to the patient for inhalation in the form of a vaporized liquid with a very small droplet diameter (less than 5 um) and is transported together with the breath into the respiratory tracts. For the reliable intake of this active substance, it is required that the vaporized liquid, and the active substance carried with it, is transported by the flow of breath far into the respiratory tracts without it depositing prematurely in the mouth and throat area. Only the transport into the deep respiratory tracts ensures an effective absorption of the active substance via the surface of the lungs. Furthermore, a synchronous coordination between the inhalation act and the generation, or making available, of the vaporized liquid is always required with the aim of providing a sufficient and simultaneously ascertainable quantity of the vaporized liquid for the dosage during the breathing act. In view of both of these requirements, it has been already recognized, in the use of dosing-aerosols, that a stream of vaporized liquid generated by means of spray diffuser, introduced into the inhaled air stream by the breathing act, is introduced in too strong a bundled manner into the mouth and throat area so that the desired transport into the deep respiratory tracts is not achieved. Stilling chambers, in the form, for example, of an extended mouthpiece between the atomizing location and the inhalation location, were therefore suggested which should lead to a distribution and deceleration of the vaporized liquid and enable an uncoordinated inhalation after the resulting atomization. In these, in the broadest sense cylindrically shaped stilling chambers, the liquid vapor enters into the hollow space of the stilling chamber at one front end and, due to the cross-sectional enlargement at the transition from the feed connection to the inside of the stilling chamber, an uncontrolled turbulance and, as a whole, a deceleration of the liquid droplets occurs in the stream flow. The vaporized liquid is drawn off in the breathing-in phase of the inhalation act at the opposing front end of the stilling chamber. However, as a rule in such systems, a single draw of breath does not suffice to draw the entire aerosol volume out of the stilling chamber.
In order that a sufficient quantity of the vaporized liquid is provided for the inhalation step, the hollow space of the stilling chamber must be relatively large so that dead spaces can arise in which the vaporized liquid can completely come to rest during the uncontrolled turbulence occuring in the available volume. During the atomization, these regions low in interchange are only filled with fresh aerosol following a large time-lag and are only emptied with difficulty again during inhalation. About 3 to 5 breaths are required for complete evacuation. On account of the long sojourn time in these regions, the droplets can settle on the walls of the stilling chamber. Therefore, the stilling and the homogenization of the vaporized liquid in such systems is insufficient. A further disadvantage is the large volume required which is difficult to handle for the patient in particular, in transportable inhalation devices.
An inhalation vessel of plastic is known from the German utility model G 89 08 273 which has a specialized shape in order to reduce the dimensions. The oblong main body of the stilling chamber, which at its one end, has a connecting piece for the supply of the vaporized liquid and at its other end, a withdrawal piece, consists as a whole of an amphora-like shape in which a short transition region connects with the connecting piece to enable the elliptical section of the connecting part to change over into a circular shape and from there to make up the shape of the main body in the form of a continuously increasing circular cross-section until it approaches the size of the withdrawal part again through a constantly decreasing circular cross-section after reaching a largest diameter. Thus, the cross-section of this known stilling chamber increases continously in the direction of the aerosol stream beginning with the diameter of the connecting part, and then decreases to the cross-section of the withdrawal part shortly before reaching this. However, this known inhalation vessel is actually also a very large structure in which a homogenization and deceleration of the vaporized liquid together with the simultaneous provision of a sufficient volume is achieved only with the limitation regarding its total size and thus, the ease of handling in favor of the functional purpose.
An inhalation vessel is also known which has a cylindrical atomizing space at the one front side of which a spray diffuser is centrally provided. The opposing front end of the cylindrical space has a central T-piece as a connecting element for the withdrawal part via which the inhalation ensues. In order to influence the air stream in the cylindrical space with regard to a homogenization and stilling of the vaporized liquid, a calotte, almost completely closing the cylindrical space towards the top, is provided which consists of an opening provided in its central region for the T-piece. In the peripheral region of the calotte, air flowing in from the top is guided along the outer walls of the cylindrical hollow body so that a mixing-through of the air with the vaporized liquid entering from the bottom is achieved.